It seems like getting the right 29er to fit seems like a bit of a lottery. Modern toptube lengths also seem quite compact compared with older frames back when I used to mountain bike regularly.

The trend is actually for longer top tubes than BITD in order to not have to use the stupidly long stems that we had back then. I mean, some were as long as 150mm which now would be considered ridiculous by most people.
Like I said in another post today (on a different subject) that stretched out, flat back position isn't what most bikes are designed for, now that the emphasis is on rather more technical riding than, say, 20 years ago.

The only bike that I use a stem of over 70mm on is my 1988 Explosif, where I use 90mm but with a lot wider bars (low risers) than the ultra narrow things that I handicapped myself with 20 years ago. Short stems and wide bars are the way to go IMO.

But what I don't understand is to get good stand over clearance I have to go down to almost an 18" on a 29er by the looks of it. Then I have a long broomstick for a seat post and still a fairly long stem.

I guess I've spent too many years being a roadie. It gives me too much lower back pain being sat up too much on a mountain bike. Maybe I'm stuck too much in the 90's when it comes to Mountain bike frame geometry.

Study the geometry. Of that bike and others. Launching into 29er makes extra to learn about. I found riding retro again for a few rides got me set up understanding where I'm upto. And I've been dodging big frames. My biggest retro is a long and tall 20" muddy fox with 120 stem I defo don't want bigger Bizarrely in this case for top tube length reasons, so I size down, maybe it's cos as the seat goes up at 73 degrees it's a long reach across and down then! You may find that at your height, obviously it should be a large you may be in between, plus 29ers tend to be smaller framed to take into consideration bigger wheels, plus slightly longer forks and that headtube, maybe all those bits and pieces makes your overall bike experience more like a 22" and that was big BITD! Trend now is technical and low slung longish frames run with short stem so to me it looks a little long and tall, great for commutes, tow paths and easy xc but perhaps not for more technical or drop offs etc. I may not be as knowledgable as some of the hardy riders here, I'm I between sizes it seems so finding my happy MEDIUM!

I ride 29ers with both low and high ST frames. Poor standover on XL Singular frames for the singlespeed did/does not bother me. But then Holland IS flat, on challenging trails it may be more of an issue.

Your seat post extension says you could go down a size.
But the position of the saddle in the clamp it says not.
Maybe the Unit just is not a very good fit for your preferences?

One size down Unit you loose half an inch on the Top tube to gain an inch standover. YMMV.

you have a conflict here - the seat being set as far back as it is is shouting out "too short a top tube so buy a bigger frame" but the lack of standover hieght is saying "buy a a smaller frame" - you can only have one.

.... actually just seen that your seatpost has zero layback so there is 20 - 25 m to be gained there.

if the lack of clearance is an issue, you need to go to a smaller frame.

how long is the horizontal top tube on that bike? The trend is to have longer top tubes - for a 20 inch frame it should be around 610 mm, over 600 mm for sure.

A layback seat post would get the saddle back in the middle of the rails that would be good.

Top tube is 24.3 inches long. (61.7cm).

I've seen a used rigid fork for sale that has a 450mm A-C measurement. That would give me 2-3" of stand over and a more aggressive position on the bike. I'm not a big fan of front suspension anyway. I've also been looking at the original specs for the bike. Currently the BB is 13.5" from the floor, originally with the rigid fork it would be 12.2". So the front is a bit high.

If I go down a size in frame I end up with a longer stem. I have a feeling I'm just going to either swap the frame or get rid of the bike. I've also been looking at the inbred spec's. Looking at there guide I'm either a 19.5 or a 21". I don't want to spend more money and end up with not really that much difference in stand over clearance.

But what I don't understand is to get good stand over clearance I have to go down to almost an 18" on a 29er by the looks of it. Then I have a long broomstick for a seat post and still a fairly long stem.

...

It's normal to have a longish seatpost on a bike with decent frame clearance.

I've seen a used rigid fork for sale that has a 450mm A-C measurement. That would give me 2-3" of stand over and a more aggressive position on the bike. I'm not a big fan of front suspension anyway. I've also been looking at the original specs for the bike. Currently the BB is 13.5" from the floor, originally with the rigid fork it would be 12.2". So the front is a bit high.

Lots to think about.

Personally I think a fork of 450mm A/C is too short for that frame - I wouldn't entertain anything less than 470mm unless you want to end up with an overly steep head angle, which will be as big a handicap in technical going as a too-long stem. Combine the two and the forecast calls for pain.......

Inline post, short (60-70mm) stem and wide (700mm+) bars with the forks that you already have and forget about road bike fit conventions. Get it in some tight, steep techy conditions and you'll see that "long and stretched out" isn't necessarily the way to go.
Yes, you need a decent length top tube (which you have) but not with a huge long stem too. Go wider on the bars rather than further ahead, in other words.

You only have to look at old mtb footage from BITD to realise how crap the fashion for long stems, narrow bars and overly big frames was. Endos galore on stuff that we'd ride with one hand behind our backs now. I have to say, in my defence, that I wasn't as much a victim of this as some but, nevertheless, my 1988 Explosif rides a lot better with a short stem and wider higher bars than it ever did when I was racing on it back in the late 80's/early 90's. Top tube's a bit short now, of course, but you can adapt to it.

Personally I think a fork of 450mm A/C is too short for that frame - I wouldn't entertain anything less than 470mm unless you want to end up with an overly steep head angle, which will be as big a handicap in technical going as a too-long stem. Combine the two and the forecast calls for pain.......

Inline post, short (60-70mm) stem and wide (700mm+) bars with the forks that you already have and forget about road bike fit conventions. Get it in some tight, steep techy conditions and you'll see that "long and stretched out" isn't necessarily the way to go. Yes, you need a decent length top tube (which you have) but not with a huge long stem too. Go wider on the bars rather than further ahead, in other words.

You only have to look at old mtb footage from BITD to realise how crap the fashion for long stems, narrow bars and overly big frames was. Endos galore on stuff that we'd ride with one hand behind our backs now. I have to say, in my defence, that I wasn't as much a victim of this as some but, nevertheless, my 1988 Explosif rides a lot better with a short stem and wider higher bars than it ever did when I was racing on it back in the late 80's/early 90's. Top tube's a bit short now, of course, but you can adapt to it.

Your right, i'm going to leave the short 450mm fork. I like everything about the bike. Toptube length is great. The only problem is the standover height. It's my first single speed and I love it. Really love the sliding dropouts as well. I'm looking for a frame swap. Either an 18" or 19" in a Kona Unit or On-one inbred 29er with sliding dropouts.

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